The control of ozone levels in the ppm range is a very important tool i.a. for the sterilization of materials, e.g. preparations for medical use, equipment and apparatuses, where ozone is used for eliminating harmful and unwanted species. Ozone is a substance with excellent qualities to kill microbiological entities such as virus, bacteria, spores and fungi. As ozone is toxic to these entities already at low concentrations (ppm-range) it is imperative to be able to control and measure ozone on-line in real time. Such a method would be highly valuable for cleaning, disinfection and sterilization of various types of equipment and processes, such as medical devices, food and beverage processing equipment as well as in agriculture and breeding environments. The method could also be used for measuring the oxidation of organic material in the development and manufacturing of microelectronic products and production methods.
Ozone detectors according to prior art have been based on a number of different methods. Most methods require use of some kind of reagent, which means that either a sample must be withdrawn from the system in which the ozone is to be determined, or one has to accept a contamination of the system. The latter is unacceptable in e.g. sterilization of water for medical purposes. Spectroscopic methods would not cause such interferences, but requires fairly complex systems that are expensive. Also, they require the provision of windows in the light paths, where clogging can occur causing drift problems over time.
In WO 99/13325 there is disclosed an electronic tongue based on electrical pulses according to a pulse programme comprising a plurality of pulses in sequence and at different amplitudes, being applied to electrodes. The electrical pulses are i.a. selected from voltage pulses and current pulses. The obtained response signals are used as input to a pattern recognition program in a computer for interpretation and for outputting results indicative of a desired property of a sample, such as the concentration of an analyte, pH etc. The analysis is based on multivariate methods, such as PCA (Principal Component Analysis). A brief account of PCA is given in an article by F. Winquist et al in “An electronic tongue based on voltammetry”, Analytica Chimica Acta, 357 (1997) 21-31. This article and the WO publication are both incorporated herein in their entirety by reference.